Ballasts are used in the artificial illumination arts for starting and controlling power applied to lamps, such as fluorescent lamps and high intensity discharge (HID) lamps. These types of lamps are often installed as recessed down-facing lights (also known as recessed can lights) in so-called recessed can fixtures that are recessed into ceilings or walls to provide unobtrusive directed lighting source. Ballasts installed in such recessed can fixtures are not typically covered by insulation. If the insulation is improperly installed, then heat may build up, increasing the heat retained by the lighting system and a rise in temperature. This poses a fire danger and safety hazard. To prevent this hazard, a detection system may be employed to detect a rise in temperature and shut off the electrical current before the increase in temperature and the heat buildup poses a safety concern. A conventional insulation detector includes a resistive heating element which is thermally coupled with a bi-metallic switch, with the heating element connected across the voltage supply mains and the bi-metallic switch in series with the input to the ballast. In the event the insulation is packed too close in the fixture, the internal temperature of the insulation detector will rise and cause the bi-metallic to open, thereby discontinuing the power to the ballast circuitry. However, the connection of the resistive heating element across the input supply mains renders the ballast and associated insulation detector appropriate for only a fixed input voltage rating. Prior attempts to regulate the voltage across the insulation detector heating element have degraded the total harmonic distortion (THD) generated by the ballast. Consequently, there remains a need for improved ballasts and techniques for powering heating elements of insulation detectors without exacerbating THD levels for recessed can lighting installations.